1. Field of the Invention
The present invention relates to expansion joints of the type which enable adjacent concrete sections separated by an expansion slot to expand and contract. More specifically, the invention relates to roadway expansion joints which seal out water and debris on the roadway surface from entering the expansion slot.
2. Description of the Prior Art
Concrete roadways are made with concrete sections which are separated by expansion slots to accommodate thermal expansion and contraction of the roadway. In the prior art, roadway joints were sometimes sealed by first inserting a rod or other rigid insert within the slot and then applying a caulking material to form a seal over the top of the joint. The caulking materials used included tar and bituminous elastomer mixes, and the like. This type joint has been found to be problematical because of a lack of adhesion between the caulking material and the adjacent concrete sections. This loss in adhesion is due to the movement of the concrete which causes a strain on the adhesive bond between the caulking material and the concrete. Once the seal is lost, water and debris from the roadway can intrude between the concrete sections and deteriorate the roadway. An example of such a sealed construction is shown in U.S. Pat. No. 3,124,047, issued Mar. 10, 1964, to Graham.
In another type of prior art joint, a rubber compression seal is compressed and inserted into the slot of the joint. This type seal also fails with time, since continued expansion and contraction movement of the concrete sections eventually cause the resilient material to take a "set" so that subsequent expansion of the concrete sections results in a leak occurring. Compression type seals are shown in U.S. Pat. Nos. 3,718,403; 3,387,544; and 3,521,528, for instance.
It is also known to use a metal plate to bridge the expansion slot, the plate being secured to the recess in one of the concrete sections and being movable relative to recesses in the other of the concrete sections. The recessed portions above the plate are typically filled with an elastomeric material. Such a joint is shown, for instance, in U.S. Pat. No. 4,279,533, issued July 21, 1981, to Peterson et al. Other of the prior art joints have included premolded members which were mechanically secured within the slots as by bolts. These solutions are less than satisfactory in that they lack durability or require very demanding quality control in construction.
The present invention has as its object, the provision of a roadway expansion joint which effectively prevents the intrusion of water and debris from the roadway surface over an extended time period.
The invention also has as its object the provision of such an expansion joint which can be produced at low cost and with excellent quality control.